Numerous compounds showing antineoplastic activity have been identified in the organic solvent extracts of plant material, microorganisms and marine organisms. Further investigation into the utility of these compounds as chemotherapeutic and anti-HIV agents has been hampered by their low natural abundance and the inefficiencies of conventional extraction techniques. An example of one such compound is taxol (NSC 125973), a diterpene plant product derived from the western yew Taxus brevifolia. The conventional organic phase extraction and chromatographic purification process for preparing taxol is time consuming and could also be harmful to the biologically active compounds because of their long residence time in a harsh environment. This technique is also encumbered by low overall yields. The specific aims of this application are to investigate the application of supercritical fluid extraction and chromatography to the isolation and purification of natural products with anticancer or anti-HIV activity.